One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,7)(6,8)(18,21)(22,24)(25,26,29,30)(27,31,33,34)(28,36,37,32)(35,40,39,38)(1,3,5,8)(2,4,7,6)(10,13)(14,16)(19,23)(22,24)(26,30)(27,33)(32,36)(35,39)(1,3)(2,6)(4,7)(5,8)(9,10)(11,14)(12,13)(15,16)(17,18)(19,22)(20,21)(23,24)(25,26)(27,34)(28,32)(29,30)(31,33)(35,40)(36,37)(38,39) involution — undirected(1,3)(2,6)(4,7)(5,8)(17,19,20,23)(18,22,21,24)(25,27)(26,31)(28,35)(29,33)(30,34)(32,38)(36,40)(37,39)(1,4,5,6)(2,3,7,8)(9,11,12,15)(10,14,13,16)(25,28)(26,32)(27,35)(29,37)(30,36)(31,38)(33,39)(34,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.